2216	2008-10-09 01:29:10	brainerd@wildblue...	UHFSDR
Message	Date	From	Subject
I posted the revised schematic and the board layout for my UHFSDR at <http://wb6dhw.com/Under_Development.html> After I let these set for awhile, I will recheck them and have a few prototype boards made. When the boards get into production, Art will be offering a parts kit. The UHFSDR will be a 1.8 to 700 MHz transceiver with 100mW output and a receiver pre- amp. Frequency control is via a Si570. Either a single antenna, or separate receiver and transmit antenna may be used. Dave - WB6DHW <http://wb6dhw.com>
2220	2008-10-09 18:29:19	Ashhar Farhan	Re: UHFSDR
dave, what prevents you from extending it t 900mhz? i'd love to use it eith openbts. - farhan On 10/9/08, brainerd@wildblue.net <brainerd@wildblue.net> wrote: > I posted the revised schematic and the board layout for my UHFSDR at > <http://wb6dhw.com/Under_Development.html> > > After I let these set for awhile, I will recheck them and have a few > prototype boards made. > When the boards get into production, Art will be offering a parts kit. > The UHFSDR will be a 1.8 to 700 MHz transceiver with 100mW output and a > receiver pre- > amp. Frequency control is via a Si570. Either a single antenna, or > separate receiver and > transmit antenna may be used. > > Dave - WB6DHW > <http://wb6dhw.com> > >
2222	2008-10-09 19:22:23	Phil Covington	Re: UHFSDR

2223	2008-10-09 19:22:25	brainerd@wildblue...	Re: UHFSDR
On 9 Oct 2008 at 23:50, Ashhar Farhan wrote: > dave, what prevents you from extending it t 900mhz? i'd love to use it > eith openbts. > - farhan > The frequency of the oscillator. The I/Q generator requires an oscillator at 2X the operating freq. The Si570 only goes to 1400 MHz. With an 1800MHz osc you could get 900 MHz RF. The ECL flip flops are rated to 4 GHz. The mixers are rated for 1 to 1000 MHz. Dave - WB6DHW <http://wb6dhw.com>
2229	2008-10-11 01:58:49	brainerd@wildblue...	UHFSDR
I have decided to add an additional sma connector on the front edge of the board and a minicircuits balun plus 2 pads on the output of the transformer to allow for the use of an external oscillator in place of the Si570. In that case, one would not install the Si570 and the interface circuitry and instead install the balun transformer, the sma connector(or a coax cable) and connect a short length of twisted pair from the output pads of the balun to the output pads on the Si570 footprint. I have modified the board for the opto isolators in place of the GTL2002. I will add the balun and sma connector before I post the modified layout(probably tomorrow, it is almost 2 AM now). Dave - WB6DHW <http://wb6dhw.com>
2230	2008-10-11 19:53:43	brainerd@wildblue...	UHFSDR
I updated the schematic and the board layout (both PDF and Gerber). Download from my "Under Development " page. I added holes in the output pads of the Si570. I also added the balun transformer and a sma connector footprint. The ground on the sma is isolated from the PCB ground. If an external oscillator is used in place of the Si570, the Si570 and interface are omitted and a twisted pair connected from the output pads of the Si570 to the testpoints next to the balun transformer. I also embeded a soic-8 footprint inside the DIP-8SM footprints for the 6N137's. Another opto coupler may then be substituded that has a compatable pin-out. Dave - WB6DHW <http://wb6dhw.com>
2232	2008-10-12 00:25:00	Art	Re: UHFSDR
Dave, Since you are in the design phase, I wonder if you would consider using a Coilcraft parts instead of Mini-circuits. Mini-circuits generally cost significantly more and are a nightmare for International users to obtain (very high shipping charges to International users). I understand the reason for buying ready made rf transformers, but a homebrewed transformer would on a toroid is generally cheaper and the cores are available from multiple vendors rather than a single vendor in the case on Mini-circuits. Regards, Art > a minicircuits balun plus 2 pads on the output of the transformer > to allow for the use of an >external oscillator in place of the Si570.
2233	2008-10-12 00:42:01	brainerd@wildblue...	Re: UHFSDR
On 11 Oct 2008 at 12:28, Art wrote: > Dave, > > Since you are in the design phase, I wonder if you would consider > using a Coilcraft parts instead of Mini-circuits. Mini-circuits > generally cost significantly more and are a nightmare for > International users to obtain (very high shipping charges to > International users). > > I understand the reason for buying ready made rf transformers, but a > homebrewed transformer would on a toroid is generally cheaper and the > cores are available from multiple vendors rather than a single vendor > in the case on Mini-circuits. > > Regards, > > Art > > > a minicircuits balun plus 2 pads on the output of the transformer > > to allow for the use of an > >external oscillator in place of the Si570. > Yes I would like to use equivilent Coilcraft. I don't see any Coilcraft transformers > 1200 MHz or Baluns. I think I speced Coilcraft for the other transformers. Dave - WB6DHW <http://wb6dhw.com>
2242	2008-10-13 19:30:39	brainerd@wildblue...	UHFSDR
I just uploaded the latest schematic and board layout. I moved the holes for external clock connection to just outside of the Si570. I also aligned all of the connectors on a .1" grid. Dave - WB6DHW <http://wb6dhw.com>